Raquel Romero
2009
Catskill Aqueduct is the water source for New York City water system which
provides water for the city of Yonkers. Imagine if that water system broke down.
Yonkers backup water would have to substitute. Did you know the Saw Mill River is
Yonkers backup water source? I don’t know about you but I would want my water
system to be a healthy one. So what is it that makes a river healthy? Well one major
aspect of a healthy river is its biodiversity. The more diverse a river is the healthier it is.
Biodiversity or Biological diversity is defined as the sum of all the different
species of animals, plants, fungi, and microbial organisms living on Earth and the variety
of habitats in which they live. Biodiversity is important to maintain because it acts
like“glue” that prevents ecosystems, for example, from collapsing. If there aren’t enough
producers and consumers, then an ecosystem can collapse and that would cause problems
in the environment. This would be an example of ecosystem diversity (Eldredge 1).
There are three ways in which biodiversity is identified and they are listed as
follows: genetic diversity, species diversity, and ecosystem diversity. Genetic diversity
refers to the total number of genetic characteristics in the genetic makeup of a species.
Species diversity refers to the number and distribution of species in one location.
Ecosystem diversity refers to the diversity of a place at the level of ecosystems (Eldredge
1).
Biodiversity is an important topic to focus on because of its value to the natural
environment. It supplies the world with food, shelter, medicines, etc. It also provides
non-material benefits like recreation. Biodiversity is also a measure of health to an
environment. The more biodiverse the ecosystem is the healthier it is, there fore the more
it benefits us. Biodiversity affects regulating services that regulate ecosystem processes,
climate, floods, disease, and water quality (“Ecosystem Change” 1). This is why keeping
the environment diverse is crucial to our survival.
In testing certain areas for biodiversity, there are several ways one could
calculate this. The Shannon Weaver diversity index is one approach one could make.
A diversity index is a mathematical measure of species diversity in a community.
Diversity indices provide important information about rarity and commonness of species
in a community. The ability to quantify diversity in this way is an important tool for
biologists trying to understand community structure. The Shannon Weaver Diversity
index is one of several diversity indices used to measure diversity in categorical data.
Shannon Weavers index calculates both abundance and evenness of the species that are
present. The proportion of species i relative to the total number of species (pi) is
calculated, and then multiplied by the natural logarithm of this proportion (lnpi). The
resulting product is summed across species, and multiplied by -1 (“Shannon index” 1).
This allows diversity to be measured and analyzed in an organized manner.
Another diversity index includes Importance Values. These are numbers range
from 0-3 that gives an idea of the ecological importance of species in an area based on
frequency, area, and dominance. Zero would equal low ecological importance to where
three would equal very high ecological importance.
Although the Importance values and the Shannon Weaver Diversity index are
reasonable measures used in finding biodiversity in a community, they are the only
methods in calculating diversity in an ecosystem.
. In 1989, a study done by fish biologist Antonios Pappantoniou, showed the
distribution of fishes in the Saw Mill River in this particular year. This study was done
by taking inventory of the river at different sites, identifying the species of fish,
categorizing them as abundant, common, rare, or Hudson River, and graphically plotting
them (Hall, 2008). These methods provided a total of 1967 specimens representing 12
families and 22 species, found in the river.
The Saw Mill River is twenty miles from Chappaqua to Yonkers; the Saw Mill
River is a major natural resource in Westchester County and a critical riparian corridor
(stream). It is the county’s southernmost tributary to the Hudson River and provides some
of the only remaining habitat in this part of the county for a wide range of plants and
animals.
The river has been home to over 20 species of fish and was widely known among
Northeastern Native Americans as the “Great Fishing Trap” because of its abundance of
fish. Species that have been found there include the White sucker, the Black nose dace,
Long nose Dace, Common Shiner, Bluegill Sunfish, Golden Shiner, etc. The river’s fish
help maintain its ecological balance and serve as indicators of its overall health. However
after years of reconstruction, alterations, and increases in industry, the Saw Mill River
could be one of the most polluted rivers in Westchester County (“Fish Study grant” 1).
Previous studies have been done on the Saw Mill River in the last two decades
that indicate fish diversity is declining, and existing fish populations are diminishing in
number. The studies include one by Ferry Sloop (Saw Mill River Coalition precursor)
and another by fish biologist Antonios Pappantoniou at Lehman College in 1989 and
2003. A way to try to help resolve this occurrence is by conducting a fish study in the
Saw Mill River and seeing if fish species are still decreasing. Groundwork Hudson
Valley announced that a $30,000 grant has been received from Westchester Community
Foundation to conduct a comprehensive fish study of the Saw Mill River in 2008 (“Fish
study Grant” 1). This study will allow a more thorough analysis of the river.
This study was carried out throughout the months of June, July, August, October,
April, and May. It was completed in spring 2009, a report, including findings and a
comparison of results with prior studies, will be distributed to local decision makers and
planners, developers, other Coalition members, and nonprofits.
This study will hopefully lead to a great improvement in our community.
Because the Saw Mill River is considered to be the backup water source for the city of
Yonkers, this study should be of great importance to everyone. The best way to prevent
loss of biodiversity in this river is by not polluting wastes, garbage, etc. onto the streets,
because it will eventually end up in the river by means of runoff. Also inform others of
the importance of fish diversity and what they can do to prevent its loss.
Analysis of The Saw Mill River
12-1-08
Raquel Romero